Are Tankless RO Systems Good? Let’s Find Out!

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Tankless reverse osmosis systems are the latest in RO water filtration. With their sleek, portable designs and space-saving functionality, why wouldn’t they be?

A wise person once said to me that: ‘Just because something looks good, doesn’t mean it is good’, which can be applied to a lot of things in life.

Does it apply to tankless RO systems as well? Let’s see.

Key Takeaways

  • Yes, tankless RO systems are good, both under-the-counter and countertop models.
  • While any RO model will have its pros, cons, and limitations, a tankless RO system is a good choice for most at-home water filtration setups.
  • General advantages of tankless reverse osmosis systems (with internal pump): Compact, higher contaminant reduction rates, fast filtration, easy to install and maintain, no stagnant water, low wastewater production.

Are Tankless RO Systems Good?

So, are tankless RO systems good? Yes, tankless RO systems are good. In fact, they are excellent, particularly ones that use an internal pump.

  • Tankless reverse osmosis systems have a very high contaminant reduction rate when properly operated and maintained.
  • They are generally easier to install and maintain, and they take up considerably less space than tank models.
  • They provide fresh water as needed, rather than having water sitting in a storage tank.
  • They only waste a small percentage of the feed water.

What Is a Tankless Reverse Osmosis System and How Does It Work?

Not only do tankless reverse osmosis filter systems take up much less space, but they also can create fresher water on demand thanks to their powered internal pump.

This pump works to push water through the system and the reverse osmosis membrane at a high-pressure rate, creating a consistent water flow with minimal wastewater compared to the tank models.

blue reverse osmosis membrane

How do they work exactly?

They usually connect to the cold water supply under the sink or at the existing kitchen faucet.

The cold water enters the system and passes through pre-filtration, where sediments, chlorine, and other chemicals and contaminants are being removed. This improves water quality by a great bit and protects the RO membrane from fouling.

The membrane itself removes pretty much all remaining impurities: Heavy metals, salts, metalloids, pesticides, herbicides, etc. Any rejected contaminants are flushed down the drain line.

Post-treatment may include activated carbon filtration, remineralization, and UV disinfection.

Finally, the pure RO water flows out of the faucet ready for use.

Are You Better Off with a Tank-Based Filter System?

Both tank and tankless systems are effective, so it really is a matter of personal needs and preference when deciding which one to buy.

  • For example, if you need to hook up your coffee maker or ice machine, then you will want to go for a tank model as the tankless ones often aren’t capable of this.
  • If you are short on space, then a tankless is a no-brainer. Tankless are more expensive but may save you long-term on the water bill as they produce less wastewater.
  • Tankless produce fresh water on demand but then will not work if there is an electricity cut, whereas a tank model will have some clean water already stored.

What’s Different

The main differences are how the water is stored and delivered. Tankless models will need electricity to power their booster pump, which will create the on-demand water.

Models with a tank store filtered water coupled with pressurized air, which forces the water into your faucet without the use of electricity.

Pros of Tankless Reverse Osmosis Water Filter Systems


Tankless systems are smaller by a long shot. If you have limited under-counter or countertop space, having an option half the size of a tank system is a huge pro.

Waste Water

Tankless systems generally create much less waste water. Standard systems with a tank tend to make about 3 to 5 gallons of waste water for every gallon purified, whereas tankless combined with a pump can produce as little as 0.25 gallons of waste water for every gallon of purified.

Contaminant Reduction

A tankless system may even be slightly better at this, as the pressure pump used can actually make the RO membrane more effective, which filters out more contaminants.

Secondary Pollution

Eliminating the need for a tank also eliminates the risk of secondary pollution. Secondary pollution is when microbes gets into your tank and grows, re-contaminating the stored, purified water. But even without bacteria and the like, an RO storage tank may leach plastic taste into the RO water.

Under Sink Reverse Osmosis System

Filtration Speed

The tankless system’s pump creates water on demand and has an increased amount of gallons per day it can filter.

Installation & Maintenance

It is considerably easier to install and maintain tankless systems, some of which are as simple as hooking them up and going. As for maintenance, you don’t have to monitor storage tank pressure, check and ASO valves, or any issues with tank performance.

Cons of Tankless Reverse Osmosis Water Filter Systems


Tankless systems usually have a higher initial cost, but if you get one that produces less wastewater, you may save money on your water bills over time.

Power Outage

A tankless RO system needs electricity to work properly. If there is a power cut or blackout, you must store containers of purified water away to have it available for that time.


Overall, tankless systems are louder than tank systems, due to the electric pump.


Most tankless systems do not allow for any customization. Tank systems, by comparison, can often connect to your ice machine or coffee maker, and you can add extra filtration steps.

What to Consider When Shopping for a Tankless RO System?

The Filtration Process

Have you had your source water tested? This is important to see if an RO system is right for you. If it is high in certain contaminants, you may need certain pre-filtration installed.

So if you have elevated chlorine levels, then you need at least one good carbon pre-filter. The same applies to sediments or stuff like iron.

NSF Standards

Purchasing a machine that lists its NSF certification is important. These certifications show that the device has been tested to ensure it can filter contaminants properly and is made with high-quality material.

Remineralizing the Water for Drinking

RO removes essential minerals from the water, along with contaminants. While we can get these minerals elsewhere from our diet, some prefer remineralizing their RO water with a post-filter. If this is the case for you, make sure you invest in a system that has or that can add one.

young woman drinking water

Your Home’s Water Pressure

If your water pressure is generally low, you may need to install an extra pump or purchase a system with an inbuilt pump – which is often the case with tankless RO systems.

This will help keep the water pressure from a tankless system steady and will also reduce the amount of waste water. Speaking of…

Drain to Pure Water Ratio

Check the wastewater estimates when purchasing a reverse osmosis system. Some models will be considerably less wasteful than others.

Filtration Capacity

Check the life of your filters, and take into consideration that if your feed water is particularly heavy in contaminants, the filters may have a shorter lifespan.

Also check how much it will cost you to run a particular reverse osmosis system long-term.

If you have any thoughts about the question, are tankless RO systems good, please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
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